Consider the resonance structures of formate. Select the true statements about the resonance structures. The actual structure of formate is an average of the two resonance forms. Each carbon-oxygen bond is somewhere between a single and double bond. The actual structure of formate switches back and forth between the two resonance forms. Each oxygen atom has a double bond 50% of the time.
The Correct Answer and Explanation is :
The formate ion ((HCOO^-)) has two major resonance structures, which are the same in terms of bonding but differ in the distribution of the charges and the placement of double bonds between carbon and oxygen. In the actual structure, these two resonance forms contribute equally, leading to an average structure.
Now, let’s break down the provided statements:
- The actual structure of formate is an average of the two resonance forms.
True. The resonance forms do not exist as separate entities; rather, the true structure is a hybrid (average) of the two forms. This means that the bonding and electron distribution in the molecule are an intermediate between the two resonance structures. - Each carbon-oxygen bond is somewhere between a single and double bond.
True. In the resonance hybrid, the bond between the carbon and each oxygen atom has partial double bond character. This is because the actual structure is an average of the two resonance forms, where one bond is a single bond and the other is a double bond. - The actual structure of formate switches back and forth between the two resonance forms.
False. The structure does not switch back and forth; rather, the two resonance structures are in equilibrium, contributing simultaneously to the overall electron distribution. - Each oxygen atom has a double bond 50% of the time.
False. In the resonance hybrid, both oxygen atoms have a partial double bond character, but neither is a true double bond for exactly 50% of the time. The electrons are delocalized across both oxygen atoms, meaning both are equally involved in bonding with carbon, not switching between single and double bonds.
So, the correct answer is that the first two statements are true, and the last two are false.